To replace the quarter turn fastener springs 5325-00-449-3001 [5325004493001] (Item 5 above), drill out the existing rivets 5320-00-083-5009 [5320000835009] (Item 6) with a 1/8″ drill bit.
These parts can be substituted as follows: First, the quarter turn spring can be substituted with Dzus or generic quarter turn fastener springs with the dimensions of spring height to latching surface .150″ to .175″ and measurements of 1-3/8″ eye to eye. Second, the rivets are simply 1/8″ diameter x 5/16″ length.
It is not uncommon, when replacing the Time Delay Module, to encounter stripped mounting holes. This is primarily because the mounting surface is aluminum, and people often overtorque the screws anyway. We attempted to use #10 sheet metal screws to mount the Module, but there was insufficient material to hold the screw.
We initially attempted to use 10-32 x 1/2″ flanged screws with washers and nuts on the underside:
As you can see, the rearward screw cocks sideways. Although functional using the nuts on the backside, it was extremely difficult to accomplish, and would not be “user-friendly” when and if replacement was necessary. We removed the Module and decided to use rivet nuts (“nutserts”).
We intend to use 10-32 x 1/2″ screws, and acquired 10-32 rivet nuts intended for thin or sheet metal. The holes need to be drilled out to the outside diameter of the rivet nut.
Next, confirm the rivet nut is threaded correctly by inserting the screw into the rivet nut.
Next, thread the rivet nut onto the rivet nut gun and crimp into the drilled holes.
Once again, thread the intended screw into the crimped-in rivet nut to confirm threads are undamaged.
For final installation, we installed stainless steel screws and placed star lock washers to ensure they will not back out during operation.
Although not necessary for a serviceable vehicle, generally replacing a worn or missing instruction plate is a worthwhile endeavor. The left picture shows the face of the plate that goes over the fording valve handle. The right picture shows the NSN of 9905-01-205-8635 [9905012058635]. It also appears to have an AM General P/N of 12339109
Left side, hose 4720-01-196-1636 designed for early version; Right side, hose 4720-01-360-2380
As our M1038 was an extremely early version, we assumed it would use the hose for the earlier version 4720-01-196-1636 [4720011961636] (Fig. 27, Item 7). However, we apparently had a later version tank 2930-01-256-5350 [2930012565350], so we required hose 4720-01-360-2380 [4720013602380] (Fig. 27, Item 9).
We note that we installed the hose intended for the earlier tank and could have simply cut off the excess length. However, there is a slightly different bend that gave us some concern about clearance with the radiator side shield. (After we installed the side shield, however, it was clear that cutting the earlier version hose would clear)
We were unable to locate specifically where the vent line from the rear routes around the right motor mount. We crawled under one of the M998s on the ranch and were able to snake a cell phone up to take some pictures.
Lower Red Arrow – Vent line from rear of vehicle; Upper Red Arrow – Fuel Tank Vent line to filter/intake stack; Lower Green Arrow – Fuel line from tank; Upper Green Arrow – Return line to tank.
As best as we can tell, there is simply no cushion clamp to mount the vent line, and it lays across the frame between the motor mount and the body mount (just under the mount flange riveted to the body).
Lower Red Arrow – rear vent line; Upper Red Arrow – fuel tank vent line
Viewed from the rear of the RH front body mount, it is clear that the rear vent line leaves the top of the frame to lay across the frame support for the body mount. Also visible is the fuel tank vent arcing upward underneath the fuel line support and cushion clamps.
Hose is Figure 398, Item 30. (The Corbin clamp is not on the vent tube at time of photo)
The arrow in the photo above indicates the position where the vent hose leading from the fuel tank vent line filter 2910-01-210-5872 [2910012105872] (behind the surge tank) is to be placed for clearance when the hood is closed. Note a Corbin style clamp 4730-00-954-1251 [4730009541251] needs to be placed on the hose ends both where the hose attaches to the tube and to the filter.
The callout for this hose is for an 11″ length of CPR104420-2 (replaceable with 3/8″ air brake tubing, such as Eaton Synflex®). We instead replaced this with 1/4″ SAE J30R9 hose (which we consider a modern and equal substitute for RB1450-1-4IDX1-20D).
Our reasoning for using hose instead of tubing is based on a couple factors: First, it is called out as RB1450-1-4IDx1-20D (or equivalent) to connect the fuel tank vent line to the fuel vent line filter (See Figure 18, Item 6). We are of the opinion the hose leaving the vent line filter should be the same as the hose entering the filter, and that indication of tubing may be an error in the TM. Second, use of air brake tubing essentially requires a heat gun to soften the tubing enough to slide over the tube on the stack and bead on the filter itself. Although this can be accomplished, should field repairs be necessary, it essentially requires cutting the tubing, where the hose can be easily removed by loosening the Corbin clamps.
Note: the drawing indicating the vent line hose appears to be the same as the hose entering the vent, and does not appear to be tubing. Although this may be based simply on the artist, we are of the opinion that the hose leaving the vent should be the same as the hose entering the vent.
We note the installation instructions for the DWF kit also indicates the CPR104420-2. See http://www.hummerknowledgebase.com/driving/dwf.html (at Image 3), where is specifically calls out an 11″ length. (We do, however, note this document is extremely dated, as it calls out for use of Dexron II at Image 5). Dexron II was long ago deprecated: In 1993, GM released new Dexron-III fluid (GM Spec GM6417M and later GMN10055). As noted above, we believe the J30R9 hose is made from material superior to what was available during original engineering of the HMMWV. and stand by our recommendation to instead use J30R9 hose.
Although we have no way of knowing at this time, there may have been a UV (sun) resistance issue where the engineers preferred the air brake tubing over the hose for that reason. It may well be that the CPR104420-2 tubing has a greater resistance to breakdown that the RB1450-1-4IDx1-20D hose. However, we are around 30-some years since the original design, and materials have changed. We will monitor the J30R9 hose to determine if it exhibits any undesirable weathering characteristics.
Arrows indicating locations of three hose clamps 4730-01-189-0871
Based on the call-out from the parts manual, the three hose clamps indicated below are 4730-01-189-0871 [4730011890871] or manufacturer number H68SS. Upon our research, these part numbers cross over to an SAE 68 hose clamp. Unfortunately, while size 68 clamps can be located, they are not generally commercially available. The standard (and readily available) sizes are either SAE 64 or SAE 72. We ordered both.
As it turned out (and we will post a picture later), SAE 64 is the perfect size for these three locations. We have noted that the specifications almost always call out a hose clamp considerably longer than necessary, and often leaving too much of a “tail” to grab debris, bend, and cut hands. (See photo below).
M998 Air Cleaner hose clamp showing excessive “tail” when called out part used
This hose clamp was unmodified and as received from the military. Based on what we could tell, this was a SAE 68 hose clamp.
We ordered the SAE 72 hose clamps to interchange for the clamps called out 4730-00-359-9487 [4730003599487] for use on the fording elbow 4720-01-194-5338 [4720011945338]. Although we have not yet installed these clamps, we predict they will have a considerable tail. However, those hose clamps are (for the most part) not quite as visible. On visual inspection, it appears that the SAE 68 (and possibly SAE 64) clamps may also be appropriate at that location. We will update should this information be found incorrect.
We finally were able to identify the whitish silicone-like material used to waterproof various electrical connections including the output lug on the 200 amp alternator and on the starter.
This material is Dow Corning 737 Neutral Cure Sealant. It is used in aircraft applications as a sealant on plastics, metals, rubbers, glass and painted surfaces. This is the correct material to use when rebuilding or repairing a starter, and is the material originally used during manufacture. It is available from a number of vendors, including Amazon and Ebay.
The following link provides useful information and also sells the product:
Arrow points to location of fording valve on firewall (located adjacent and behind fuel filter)
As we are replacing the 30-some year old hose and tubing with new, we need to access the fording valve to remove and replace the hoses. The below picture shows the hoses attached to the fording valve.
Picture of fording valve with arrows pointing at the three hoses attached to fittings.
Both the upper and the middle tubings are called out as P/N CPR104420-1, while the bottom hose is called out as P/N RB1450-1-4IDX1-20D. As discussed in an earlier post, the CPR104420-1 can be interchanged with 1/4″ air brake tubing, such as Eaton Synflex®. Similarly, we have determined that although not a direct interchange, we could use either 1/4″ silicone hose or 1/4″ SAE J30R9 hose (fuel injection hose). For this application, even though the silicone hose has a much higher temperature rating, we had concern about abrasion on the hose so we substituted the J30R9 hose instead of the silicone. We do however, believe that the silicone hose would be more than acceptable as a substitute under most circumstances.
The parts manual shows an exploded view of the hoses and tubing that connect to the fording valve.
Excerpt from Figure 399
As shown above, the fording valve 4820-01-192-8030 [4820011928030] (Item 2) has three hoses connected to it. The lower hose goes to the lower fitting on the DWF (Deep Water Fording) CDR valve. The middle tubing goes to a line running across the cowling and tees into the vent line from the power steering pump cap. Although this is considered a special cap for DWF applications 2590-01-192-4425 [2590011924425], it is simply a standard power steering cap with a 1/8″ nipple adapter screwed into a hole in the center of the cap.
We have diagrammed the middle hose connection (Item 7) and fording valve top connection (Item 3). to view the diagram, please refer to this updated post.
We obtained a complete fording intake stack from Alan Post. By complete, we mean the stack extension 2510-01-198-0333 [2510011980333], the clamps 5340-00-079-7837 [5340000797837], the vent tube 4710-01-209-6746 [4710012096746], and the windshield mount bracket 5340-01-238-9543 [5340012389543] with fasteners.
As you may notice, the rubber extends a little higher than normal at the base of the stack. We had ordered several 4 1/2″ silicone 90°s, to see how they would work. As it turns out, the actual AM General part is slightly less than 90°. Use of the silicone 90° required cutting the end that connects to the air cleaner at a slight “off-angle,” as did the portion that connects to the stack. We have instead ordered the correct fitting to replace this, however use of the silicone 90° would definitely be adequate and completely serviceable.
